The present invention relates to moisture impermeable end construction for cable of the type in which the cable core is a bundle of tubes.
Many fields of engineering employ to an increasing extent remote control equipment based on pneumatics or hydraulics. Accordingly, separate conduit means are needed for transmitting different control and measuring pulses, frequently over large distances. It was found suitable to use bundles of tubes being assembled in some fashion, e.g. stranded and each tube establishes one fluid signal transmission path while all tubes together constitute a multi-conduit fluid cable.
By way of example, chemical engineering uses increasingly such fluid cables for the transmission of pneumatic measuring signals or control pulses and/or for sampling gaseous or liquidous substances in a chemical plant. In the case of sampling, it may be desirable to cool or heat the cable. Fluid dynamics is preferred particularly in those cases in which the employment of electrical equipment is deemed too dangerous as defects or malfunctions may cause an explosion.
In most cases one has to provide for physical fan-out and fan-in at the ends of the cable, i.e. the tubes are to be separated from each other, as each tube must be connected to a different piece of equipment or at least to a different inlet or outlet let of such equipment. Each tube may have a different source and a different destination for the fluid passing through. The known cable are disadvantaged by the fact that upon separating the several tubes from the cable bundle for providing the different connections, the interior of the cable bundle outside of each tube, but inside of the jacket enveloping the bundle, is in effect opened up and moisture can readily penetrate the cable from both ends. The moisture may seep in, more or less slowly, but quite consistently, and the cable jacket becomes in effect a water conduit. If the tubes in the jacket are made of metal, they can readily corrode. Moreover, and particularly in a chemical plant, all kinds of substances may be solved in the water conceivably enhencing the corrosion. In many cases, the cable is exposed to ambient weather conditions, which may be quite severe, for example, on ships, tanks, off-shore drilling islands, etc. Also, in the case of heated or cooled cables, moisture may change the heat conduction properties of the cable.